1. Field of the Invention
The present invention relates to an image forming apparatus that can reduce consumption of coloring materials to be used and to a method for controlling the image forming apparatus.
2. Description of the Related Art
In an electrophotographic-type image forming apparatus, a latent image part is formed on a photosensitive drum by exposure and the photosensitive drum is brought into contact with a developing roller with toner thereon so that the toner is transferred to the latent image part from the developing roller and a toner image is formed on the photosensitive drum. In this toner image formation, a phenomenon called “sweeping” is observed. The “sweeping” is a phenomenon where a difference in the rate of rotation between a photosensitive drum and a developing roller makes toner be transferred to a rear end part of a latent image part on the photosensitive drum in a rotational direction in an amount larger than to the other portions of the latent image part. In other words, the “sweeping” leaves excess toner on the rear end part of the latent image part.
A technique for preventing toner from being excessively transferred due to the “sweeping” is discussed in Japanese Patent Application Laid-Open No. 2007-272153. Japanese Patent Application Laid-Open No. 2007-272153 discusses making correction by changing density in a region where sweeping is to take place (hereinafter referred to as “sweeping target region”), according to a correction table determined in advance, based on a difference in density between in the sweeping target region and in a region located parallel to the sweeping target region in a sub-scanning direction.